In Vitro and In Situ Characterization of Fish Thymic Nurse Cells

We present an enzyme- and immuno-cytochemical, and ultrastructural characterization oftrout thymic nurse cells (TNCs). Our data suggest that isolated trout thymic multicellularcomplexes are epithelial cells with acidic compartments that may be involved in the processingof antigens and in the generation of the MHC-II proteins that these cell express, andalso that isolated TNCs are the In Vitro equivalent of the pale and intermediate electronlucentepithelial cells located in the inner zone of the trout thymus, constituting indirectevidence of the phylogenetical relationships of the inner zone of the teleost thymus withthe thymic cortex of higher vertebrates.